config & rights: use open() for better error messages

ConfigParser().read() doesn't differentiate between different types of
failure to read files, causing eg. "No such file" to be logged in all
cases, for example if permissions are insufficient. fix that by using
open() and ConfigParser().read_file() instead.

radicale/config.py

@@ -276,17 +276,18 @@ def load(paths: Optional[Iterable[Tuple[str, bool]]] = None
     for path, ignore_if_missing in paths:
         parser = RawConfigParser()
         config_source = "config file %r" % path
+        config: types.CONFIG
         try:
-            if not parser.read(path):
-                config = Configuration.SOURCE_MISSING
-                if not ignore_if_missing:
-                    raise RuntimeError("No such file: %r" % path)
-            else:
+            with open(path, "r") as f:
+                parser.read_file(f)
                 config = {s: {o: parser[s][o] for o in parser.options(s)}
                           for s in parser.sections()}
         except Exception as e:
-            raise RuntimeError("Failed to load %s: %s" % (config_source, e)
-                               ) from e
+            if isinstance(e, FileNotFoundError) and ignore_if_missing:
+                config = Configuration.SOURCE_MISSING
+            else:
+                raise RuntimeError("Failed to load %s: %s" % (config_source, e)
+                                   ) from e
         configuration.update(config, config_source)
     return configuration
 

radicale/rights/from_file.py

@@ -56,8 +56,8 @@ class Rights(rights.BaseRights):
         escaped_user = re.escape(user)
         rights_config = configparser.ConfigParser()
         try:
-            if not rights_config.read(self._filename):
-                raise RuntimeError("No such file: %r" % self._filename)
+            with open(self._filename, "r") as f:
+                rights_config.read_file(f)
         except Exception as e:
             raise RuntimeError("Failed to load rights file %r: %s" %
                                (self._filename, e)) from e